Abstract. The demand for intercontinental transportation is increasing and people
are requesting short travel times, which
supersonic air transportation would enable. However, besides noise and sonic boom issues,
which we are not referring to in this
investigation, emissions from supersonic aircraft are known to alter the atmospheric composition,
in particular the ozone layer, and hence affect climate
significantly more than subsonic aircraft. Here, we suggest a metric to quantitatively assess
different options for supersonic
transport with regard to the potential destruction of the ozone layer and climate impacts.
Options for fleet size, engine
technology (nitrogen oxide emission level), cruising speed, range, and cruising altitude,
are analyzed, based on SCENIC
emission scenarios for 2050, which underlay the requirements to be as realistic as possible
in terms of e.g., economic markets
and profitable market penetration. This methodology is based on a number of atmosphere-chemistry
and climate models to reduce
model dependencies. The model results differ significantly in terms of the response to a
replacement of subsonic aircraft by
supersonic aircraft, e.g., concerning the ozone impact.
However, model differences are smaller when comparing the different options
for a supersonic fleet.
Those uncertainties were taken into account to make sure that our findings are robust.
The base case scenario, where supersonic aircraft get in service in 2015, a first fleet fully operational
in 2025 and a second in 2050,
leads in our simulations to a near surface temperature increase in 2050 of around 7 mK and with
constant emissions afterwards to
around 21 mK in 2100. The related total radiative forcing amounts to 22 mWm2
in 2050,
with an uncertainty between 9 and 29 mWm2. A reduced supersonic cruise altitude
or speed (from Mach 2 to Mach 1.6) reduces both, climate
impact and ozone destruction, by around 40%. An increase in the range of the supersonic aircraft
leads to more emissions at lower
latitudes since more routes to SE Asia are taken into account, which increases ozone depletion, but reduces climate
impact compared to the base case.